Abstract: Cantilever collapse is a common type of collapse disaster, which is usually found in river valley and rock slope with soft and hard slope structure. Under the action of differential weathering, rock cavity often forms at the foot of slope, and finally develops into cantilever collapse. Cantilevered collapse is a common geological disaster and characterized by toppling deformation. As the shape and size of this type of collapse are quite different, their failure modes are quite different, it is thus not able to describe its failure process quantitatively at present. Therefore, according to the deformation and failure characteristics of cantilever collapse, the judgment formula of tension failure and shear failure of cantilever collapse based on the quadratic parabola-typed Mohr criterion is established by using the mechanical analysis method. The calculation results of the judgment formula is compared with the results of the physical simulation test, and the analysis result shows that the tensile safety factor of the cantilever collapse is far less than the shear safety factor. With the crack growth, the tensile failure occurs first, and then the shear failure occurs when the crack continues to expand to a certain depth. The judgment formula can describe the deformation and failure process of cantilever collapse quantitatively and accurately, and reveal the deformation and failure mechanism of cantilever collapse quantitatively and accurately.

Key words: cantilever collapse, Mohr criterion of quadratic parabola, shear damage, tension damage